Hi BobbyC,

What Art B. says here.

The relay-fuse board, platform, or box at the center of all 700-900-90 (and probably FWD/AWD autos) is a service item now, with age, use, weather.

So, to make a short story shorter, and if you can live a few days downtime with your 700-series, it may be best to:

1. disconnect the battery

2. gain access to the relay-fuse board-box, platform.

(The the center console trim on either side, and the front center console bezel removal can be a real bother on 700-900-90 and RWD+. May want to research the procedure, find some Volvo green factory manuals online in PDF or as flash manuals, and search here on the brickboard for info.)

3. Release wire harness retainers so you have some wiggle room.

4. And one by one, remove relays, fuses, and reinstall.

5. A more throughout effort is to get underneath and look for melted wire insulation and correct.

Dave Barton offers the better terminals with the overcrimps (conductor and crimp fro insulation) that Volvo uses on the wire harness side). Continue to use a boot over the terminal if Volvo originally did so.

You may very well find (female) terminals that have failed, through corrosion, that are broken and no longer crimp to the terminal blade under the fuse or relay. These can come loose, also. You may be able to tighten these, yet, they can break doing so.

Dave Barton includes the female terminals that crimp to the conductor and over-crimp to the insulation.

http://www.davebarton.com/blackvinyl.html

Explore Dave Barton's site. There is lots of cool Volvo stuff!

See the female terminals. Sometimes called spade or blade terminals.

Use DeoxIT at these terminals. A shortcut maybe to use the dielectric DeoxIT on the fuse and relay (male) terminal. Remove fuse, relay, or at connector interface (power to device, engine control wire harness connector at ignition power stage, injector connector, AMM/MAF connector, and so on).

http://www.caig.com/

DeoxIT melts corrosion. The stuff is really cool. Yet I always forget to get some before I have such wire harness problems. So I used dielectric silicon grease, the SuperLube NLGI-2 grease in the 14-ounce tube. Helps to slow corrosion like at the 240 tail lights where the bulb holder contacts press against the bare copper contacts on the flexi circuit boards.

Also, devices and sensors all along the wire harness, usually on the power side, may have ground wires that terminate somewhere on the unibody, or some part of it. You may find a host of wires that each or a few terminate into a ring terminals, secure with a self-tapping metal screw or bolt secured to a threaded, embedded fastener. A quick loosen and tighten can help. Yet better it to remove the fastener, inspect the wires and there connection to the ring terminals. (Replace / repair as needed). Dab DeoxIT on the bolt thread and the ring terms. Stack carefully if a stack of ring terms. Install self-tapping metal screw or bolts. Tighten.

If you have a load drawing too much current, or max a fuse allows, or you have a circuit where someone installed a 25-Amp fuse where an 8-Amp fuse should be, things can get hot at the relay connection. Like a failing main fuel pump or HVAC blower.

If a self-tapping metal screw, try to align the screw thread with the thread cut into the metal so you do not blow the thread out.

Do as much as you can, and go to town. One can do this bit.

There may not be a procedure written to treat such an issue as systems corrosion in a wire harness at the bonded connection like this.

You may want to use your trusty multimeter so you can perform continuity, resistance, and voltages checks.

And see http://www.volvowiringdiagrams.com/?dir=

Though research your brickboard.com using the search function for articles threads treating this issue on 700-900-90 series Volvos.

If your 700-900-90 Volvo remains parked outdoors, and if you have any rust on the body, you have a great chance of systemic corrosion at the bonded electrical interfaces of the wire harness.

Yet even a garage queen 700-900-90, 240, and even older FWD Volvo models may have such wire harness corrosion.

As an example, please my miserable write-up, treating the backside of my 1990 Volvo 240 Dl (li'l red) Wagon fuse box. The power windows quit working, and, stupidly, the last thing I looked at was the back side of the fuse box. Corrosion at the wire harness blade or spade terminal connection to the fuse box was why. (I'd already checked the relay ground, the driver door switch and wire harness through the door hinge side. And more.)

Power windows stopped working, fixed the corrsion at the fusebox .... do'h! 200 1990

https://www.brickboard.com/RWD/volvo/1625057/220/240/260/280/power_windows_stopped_working_fixed_corrsion_fusebox_doh.html

The power windows work faster than they ever have. The headlights and tail lights are amazing brighter. And more. The thing works better. I also did this same service to the other 240s I own now. Though each time I take apart a door, or futz with something electrical, like the never ending Volvo 240 tail light saga, I check grounds, and wiggle, or open and treat with DeoxIT, wire harness connectors and grounds.

Questions?

Hope that helps you.

Sat-Your-Day Windows 10 Futzing MacDuffed

(Through Win 10 Device Manager, you may find many hardware components are using very old drivers! Win 10 update and the hardware manufacturer software update does not treat all of these drivers to update!)
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Jonathan Harshman Winters III: The Mightiest, Greatest, & Most Powerful Comedian & Comedic Actor North America in Perpetuity